Épidémiologie de l’hépatite C

Abstract

Depuis l’introduction des tests de dépistage, l’épidémiologie de l’hépatite C (VHC) a changé, en raison des mesures prises pour combattre l’infection et du développement de son dépistage. Si, au début des années 1990, la transfusion représentait la cause principale de contamination et la toxicomanie intraveineuse, de développement plus récent, était au second plan, l’inverse est aujourd’hui observé, et la toxicomanie représenterait 70 % des nouvelles séroconversions. Le diagnostic, qui était porté chez des sujets symptomatiques, l’est maintenant plus souvent devant des facteurs de risque, chez des sujets asymptomatiques. Si le pic de l’épidémie VHC semble passé, il reste encore de nombreux malades à diagnostiquer et à prendre en charge et l’on risque de continuer à assister à une augmentation de l’incidence des cirrhoses et des carcinomes hépatocellulaires liés au VHC. Les efforts doivent donc continuer, portant sur l’amélioration du dépistage afin d’assurer une meilleure prise en charge, dans le cadre de réseaux organisés autour des pôles de référence. La prévention doit viser prioritairement la population d’usagers de drogues et comporter des actions menées en milieu carcéral.

Since the availability of screening tests for hepatitis C virus (HCV) changes in the epidemiologic data have occurred, following the development of preventive and therapeutic measures and programs of large-scale screening. In the early 90’s, transfusion was the major cause of contamination and the use of intravenous illicit drug was only in the second place. At this time, HCV infection was diagnosed mostly in symptomatic patients with, in average, a 10-year duration of infection, and this delay accounts for the high frequency of liver cirrhosis at diagnosis (20 %). Since 1996, when screening by family physicians was promoted, diagnosis is made more often because of the presence of risk factors in asymptomatic patients. This accounts for most of the observed changes in epidemiology of the infection: intravenous drug use is nowadays the most frequent source of infection, whereas the proportion of transfusedborne cases has decreased. For the same reasons, hepatic lesions at diagnosis are less severe, and cirrho-sis is less frequent (10 %), despite a similar delay between exposure and diagnosis. The current causes of hepatitis C amplify these changes: transfusion-borne hepatitis have become an exception, nosocomial infections are much less frequent with the universal use of disposable devices and strict protocols for desinfecting instruments. On the contrary, the contamination by intravenous drug use does not seem to decrease and could account for 70 % of new cases of seroconversion. The epidemiological surveillance has to be maintained inside networks, and targeted testing of HCV antibodies has to be increased. Preventive measures should be directed at intravenous drug users, and include cam-paigns in jails. As a conclusion, although the peak of HCV epidemic seems to be behind us, many infected people remain to be diagnosed and managed, and the risk exists in the next years to see an increase in the incidence of HCV-related cirrhosis and hepatocellular carcinomas.